Brush attachment for electrical machines



Dec. 13, 1955 F. o. WISMAN ETAL 7,

BRUSH ATTACHMENT FOR ELECTRICAL MACHINES Filed May 25, 1951 I N V EN 0R5 rm/mwa. nag/14w BY fiamz u. #554 w 3 60m 4 TTQE/VEY United States Patent'O BRUSH ATTACHMENT FOR ELECTRICAL MACHINES Franklin 0. Wisman and Royal J. Reek, South Bend, Ind., assignors to Bendix Aviation Corporation, South Bend, Ind., a corporation of Delaware Application May 25, 1951, Serial No. 228,292

7 Claims. (Cl. 310-244) This invention concerns electrical machinery, and more particularly brush holding devices therefor.

In some electrical machines the brush holders are carried inside the machine structure in surprisingly inaccessible places where it is impossible to renew a brush Without removing parts of the associated machine. The device herein disclosed is in a sense an improvement over certain features of the brush holder described in our patent application No. 153,078, filed March 31, 1950, now Patent .No. 2,651,735. The improvement resides primarily in providing means for mounting a brush to a machine in such a manner as to permit easy replacement of the brush.

It is therefore an important object of the invention to provide a brush holder for an electrical machine on which a brush may be removably mounted without the use of bolts or screws.

Another important object of the invention resides in the provision of means for frictionally connecting a brush to a holder.

An object of the invention lies in the use of a brush attachment provided with frictional elements which not only secures the attachment to a holder but serves as current carrying conductors.

A still further important object of the invention resides in the provision of means for use on an electrical machine for pivotally supporting a brush in a manner to permit self-alignment of the latter on its associated conducting element such for example, as a commutator.

A yet further object is to provide a novel tool for re placing a brush on an electrical machine.

The above and other objects and features of the invention will be apparent from the following description of the apparatus taken in connection with the accompanying drawings which form a part of this specification and in which:

Figure 1 is a sectional view along the axis of an electrical machine incorporating the invention;

Figure 2 is a view in side elevation of the brush holder per se with portions broken away to show more clearly the manner of securing the brush to the holder;

Figure 3 is a section taken substantially on the line 33 of Figure 2; and

Figure 4 is a section taken substantially on the line 4--4 of Figure 3.

Referring now to Figure l of the drawing the reference numeral 19 designates one of the rotating parts of an electrical machine :12 to which a brush holder 14 is securely fastened by screws, not shown. The other member of the machine is designated by the numeral 18 and is provided with a face type commutator 20, on which a brush 22 rides. A flat spring 24 has one end secured to the rotating structure 10, by the aforementioned screws, not shown, and the other end of the spring is provided with an opening through which a screw 26 passes for threadedly engaging the brush holder 14. An insulating block 28 is interposed between the spring 24 and the structure 10, and is held in place by any suitable means, not shown. The manner of mounting the brush holder to the structure 10 forms no part of the invention, except to show the association of the brush holder with one form of electrical machine. Although the invention is shown in connection with a brush holder of the type unaffected by centrifugal forces acting thereon as described in our aforementioned application for patent, the invention has broader aspects, and is shown with the particular structure only as a matter of convenience and is not to be limited to such use.

Once the holder 14 is mounted to the machine 10, any brush servicing must be done through an opening 29 located in one end of the machine structure 31. This is obviously an inaccessible spot and the use of a tool to be hereinafter described, to remove a worn brush eliminates the necessity of completely dismantling the machine to reach the holder.

The brush holder 14 comprises a supporting member 30, formed with integral walls 32, 34, 36, and 38 for re ceiving the brush 22 therebetween. The area circumscribed between these walls will in general be rectangular or trapezoidal in shape for accommodating brushes used on drum or face type commutators respectively. However, other forms may be used within the spirit of the invention.

The brush 22 is removably fastened to the holder 14 by means of an attachment 42 to which the brush is secured by shunt cables 44 and 46 which pass through openings 48 and 50 in base portion 52 of the attachment. Sides 54 and 56 are formed integrally with the base 52 and extend therefrom at substantially right angles so as to permit positioning the base 52 between the walls 36 and 38. The sides 54 and 56 extend along the interior of said walls and together with the base provide a channel like construction having strength and rigidity. The sides are provided with extensions 58 and 60 which are turned outwardly and downwardly alongside said sides. That is, the extensions 58 and 60 are actually folded back on the sides 54 and 56, respectively.

The extensions 58 and 60 are crimped adjacent their edges at 62 and 64, respectively, to provide positive contact areas between the attachment 42 and the walls 36 and 38 of the holder. This contact area must be adequate to handle the current passing through the brush 22 and lead 66, to the commutator 26. One end of the lead is conductively connected to the supporting member 30 by a screw 70, the other end of the lead is suitably connected to a current source, not shown. These extensions 58 and 60 are in the form of resilient elements or fingers which frictionally engage the walls 36 and 38 along the crimped portions. These extensions 58 and 69, therefore, perform the two-fold function of retaining the attachment securely to the supporting member 30, and of establishing a current conducting path from the brush to the supporting member, as hereinbefore mentioned.

To provide for self-alignment of the brush on the commutator, the middle finger of each of the rows of fingers 58 and 60 respectively, are equipped with barbs 72 and 74 for locking engagement with openings 76 and 78 in walls 36 and 38, in that order. With this arrangement the brush and attachment are actually pivoted about the barbs. These openings 76 and 78 are located in the walls in registry with each other. The axis of pivot of the barb 72 in the opening 76 is substanitally coextensive with the axis of pivot of the barb 74 in the opening 73. Although the openings 76 and 78 are shown as passages extending through the walls, it is understood that other means may be used for engaging the barbs such as recesses or niches in the exterior walls, or lugs on the surfaces of the walls, all being within the purview of the invention.

For removing a brush from the machine of Figure 1 a tool is provided which is inserted through opening 29. This tool is furnished with inwardly turned hooks 92 3 which fit under the ends of the fingers 58 and 60. See Figure 3. Pulling on the tool forces the hooks between the barbs and the walls, thus disengaging the barbs from the openings 76 and 78. The tool may also be used for initially starting the brush into the aperture formed between the walls 36 and 38.

Although this invention has been described in connection with certain specific embodiments, the principles are susceptible of numerous other applications that will readily occur to persons skilled in the art.

Having thus described the various features of the invention, what we claim as new and desire to secure by Letters Patent is:

1. A brush holder for an electrical machine comprising a supporting member provided with an aperture for receiving a brush, said aperture being formed between opposed walls which are integral with said member, and a one-piece attachment to which a brush is secured for supporting the same in said aperture, said attachment being equipped with a plurality of opposed fingers, some of the fingers being formed with barbs thereon for engagement with the surfaces of said walls.

2. A brush holder for an electrical machine comprising a supporting member provided with an aperture for receiving a brush, said aperture being formed between side walls integral with said member, said side walls having openings therein, and a one-piece attachment equipped with fingers formed for frictional engagement with said side walls for removably securing a brush to the member, each of the side walls being engaged with a plurality of said fingers some of said fingers being formed with barbs for engagement with the openings in said walls.

3. A brush holder for an electrical machine comprising a supporting member provided with an aperture for receiving a brush, and a one-piece attachment secured to a brush, said attachment being equipped with a plurality of fingers frictionally engaging said member and providing the sole means for removably securing a brush to said member.

4. A brush holder for an electrical machine comprising a supporting member having opposing walls between which a brush is received, and a one-piece attachment to which a brush is secured, said attachment being formed with a base portion which is carried between said walls and sides from which fingers extend for engagement with the exterior of said walls, said engagement being effected by cooperating elements formed in the engaging surfaces of the walls and fingers.

5. A brush holder for electrical machinery comprising a supporting member having opposing walls between which a brush is received, and an attachment formed with two sides having a base portion extending therebetween and to which a brush is secured, said base portion and sides carried between said walls, said sides extending upwardly along the inside of said walls and equipped with resilient elements extending downwardly along the outside of said walls and in gripping relationship thereto.

6. A-brush holder for electrical machinery comprising a supporting member provided with opposing walls in tegral therewith for receiving a brush therebetween, an attachment fixed to a brush for carrying the same between said walls, said attachment having fingers which extend along the exterior of the walls in gripping relationship thereto, one of the fingers extending along the exterior of each of the walls being formed with a barb, and means formed in each of said walls to be engaged by said barbs.

7. A brush holder for an electrical machine comprising a supporting member having opposing walls between which a brush is received, an attachment to which a brush is secured, said attachment including a base portion which is carried between said walls, said base being equipped with integral fingers which extend for engagement with the exterior of said walls, and means pivotally carrying the attachment on the supporting member.

References Cited in the file of this patent UNITED STATES PATENTS 327,394 Hemsley Sept. 29, 1885 355,738 Williamson Jan. 11, 1887 442,142 Schwerter Dec. 9, 1890 924,716 Zachau June 15, 1909 987,173 Sale Mar. 21, 1911 1,761,066 Bindschedler June 3, 1930 FOREIGN PATENTS 2,098 Great Britain of 1905 27,600 Netherlands Sept. 15, 1932 484,681 Germany Oct. 21, 1929 

